Field of the Invention
The present invention relates to capacitance-detection type pressure switches and pressure sensors, and particularly, to a capacitance-detection type pressure switch and pressure sensor using a diaphragm as one electrode.
Description of the Related Art
There are well known a pressure switch and pressure sensor of a diaphragm type that detect a pressure of an operating medium upon controlling cooling and heating, air conditioning, an automobile, and a system for industrial devices. A contact type pressure switch is known as the pressure switch of the diaphragm type. However, the pressure switch of the contact type has a problem that a conduction failure possibly occurs due to the biting of foreign materials (insulating materials) into between contacts. For that reason, a pressure switch and a pressure sensor of a non-contact type such as a capacitance detection type, an optical detection type, a magnetic detection type and a strain detection type are also used.